Printing surfaces and photomechanical reproduction generally



F. G. YANES May18, 194s.

PRINTING SURFACES ANfiPI-IOTOMECHANICAL REPRODUCTION GENERALLY Filed April 18, 1944 FIG;6

FIGS

FIG. 8

INVENTOR.

FIG. 12

Patented May 18, 1948 *PRmTIN sURF cEs AND PHOTOMECHAN- IGAD'REPRODUCTION' GENERALLY *FranciscoxG. Yanes,' New York,-:N.-Y.;: Anne- F. 3 Goddard-executrixof said-FranciscoGrYanes,

1 deceased #Appiicrtionnpiiiis, 1944; 'se'riama. 531,566

(ores-+5.6)

. '20 Glaims. :1 The invention relates to improvements :1? in printing surfaces; andv photomechanical reproduction generally. "It :incl-udesrmeans, waysa'and products.

Thefimainythough not other onlypurpose of the invention: is tot-produce: printablevalues*:similar to: Z-thtose obtained by photoengraving, 2.:ph'otolithography; l and-with other varied atextures. I

i -While the: invention includes some specific forms-' which =Iare::illustratdtin the accompanied drawings, I= :Wish-Jitrtdi cc-understood; that I consider 1 those -%.examples not only v combinatively novel; but also :new in less: combination "than the whole; andesome :of its features: capable or: individual use 'as'@it wil-l' clearly appear in the course of the: pre'sentldisclosure.

jjaAlthough sthe invention mayrbe" i us'ed't in a numberl'rof: processesif I prefer etopracticerit by means; other sensitive plateflincludingv a; vsupport combiningirplura-l relief, :patterns and a special coating. This plate; after s'uitably iexposew under an: iordinary' negative and treatedflbecom'es transformed 'into a half-tohe printing-block.

: :Ina .=Di'rect method 'of -'photomechanical reproduetion described inzPatent NoZ; -2',234,-997;:issued March 18, 1941, I' suggestedra process of that kind. zi But the "means and ways now -:utilizd, the' 'products:*obtained;'aand even ;'the; principle photoengraving is, of-coursejexplainediby* the' way the image is formedg and by 'processing steps which-cause the d'ots-to close in those sections nfthe pnot-cengraving negativecorresponding to 'the -"highdights. -B ut si.ich='dual pattern is a fortunate achievement-Which contributestd the formaticn' or the richest rank of tone values In thesin'glepatterned support of formerly paitentdmethod, "the"uiiifol'mityf'bfi the- "small projections does-not" so" favor the "formation-"of tone valuea 'for the graphivelenreiits arenevelbped by the-exposure into-larger but geometricallysimilar'figures, dots into bigger-dots, lines intopoarser' linesjbut-not dots into lines.

The -structurernow suggested combines in the same body -at-.-1east two difierent kinds ofrelief patternsvat *two :different, planes respectively. Of=- these; the outer one" corresponds to a: highlight-@tint and is; purported fordevelopingthe high-lightswhil fthe inner pattern corresponds to amhalhtonewtint and is purported for the developmentfofathe -tones-and-shadows. There are 'quite ainumberof "relief patterns, both regular and irregularfi-whicl'r may be: combined: :inthe new 'arrangement; provided the high-light graphic elements: otone pattern and corresponding sections of the half-tone graphic elements-10f the othen -pattern be both situatedsubstantially ina perpendicular linex in regardto the support, wherebyy When: the lower? graphic: elements: are "raised, as -a'result'of theprocesspthe upper ones become 'embodied and. disappear into them.

nWheri the new" structure is utilized as support for: aewash off; plate Irprefer to'combine ahalfit'one'iinner pattern =formed by" cross-lines; anda hign-lightr'outer: one *formed by dots, the --smal1 projections! representing the last' protruding at the crossing points-"of the'lines. -After this supportis coated,= uptox-the ending plane-pr the projections' formingfithe--high-light"outer pat-tern, the pr'oblem presents itself-f of producing :the ph'btom'echanical "values at approximately the same operative plane; and as long as the halftone, 'lower pattern, is :under" the printing surface, the first question "is to' raise thoseerosslines by' 'the effect of light' in' depth. 1 L'etus assume that this -is done by exposingthe" plate "through its -support' and-under an ordinary negative to a beam' ofipar'allel light. *"With suflicient exposure; "and in -the sections corresponding to the tones "inthe' negative, the lines of the lower pattern will hes-raised: by additional thickness of i'iardened matter. At"the same time the dotsi'of the outer" pattern situated =in -the "same sections will'fiisappear intd theraisd lines; while those remaining' in those sections corresponding tolthe higl'i-lights win be unaffected. Such efie'ct :"or lighfi'in" depth; bf course, does not develop yet the photomechanical values in surface," for "it merely brings the two patterns to substantially thesame operative plane; and selectively soyfor dotsand cros's-lines arefthen at their corresponding'areasf But -the fundamental effect in depth 'may be subsequently complemented by aside light action whichwill" create values in "surf ace proportionally to the "transmission at dilierent areas of -the -=negative. "This second part of I the formation of the values may be attainediirmany idifferent ways, through known optical operatrons, or even* automaticallypas" in former-1y patented; method wliere" the ei fect :of light: in

seems to be new in photomeohanical reproductiorl. 1

Although a cross-line relief pattern is most suitable for developing a good rank ofhalf-tone values, it appears inadequate for a single*pat-,

terned support, because the minimum tint would be too gray to represent the conventional whits" in half-tone prints. It has been found, however, in the process of the invention, that while the coating of a. dual patterned support ends at the vertices of the high-light graphic elements of the outer pattern, the same coating, in regard to the inner pattern situated atv a lower plane is, in fact, an ovcrcoating. Therefore, if We eliminate from the dual patterned support the dotted outer relief, and still coat the plate as if it were present, the attainable result will be a photorelief with the richest rank of halftones and in which the minimum dots have disappeared. The final print in this case will show pure whites, as in the so called lithographic half-tones. This variation seems to be specific ally new, for the fundamental single patterned relief will be a half-tone tint instead of a highlight one, and because the coating will not end at the printing plane of the tint plate but relatively far above the same.

It will be later noticed that the projections utilized in the chosen example of dual patterned structure have a shape which is different from that characterizing the graphic elements of my formerly patented method. In the last, the projections, whether dots or lines, actually have bodies decreasing in cross-sectional area and sharply ending at the same plane,'a condition which is essential in that process because the transformation of the values in depth into values in surface is the result of the shape given by the relief pattern to the sensitive coating. Such is not the case in the present disclosure, where the formation of the photomechanical values is based upon an entirely new principle, It is possible, of course, to utilize the type of projections of my formerly patented method for building up the new dual patterned structure, and indeed that method would be improved by the better rendition of tone Values achieved through the metamorphosis of the dot. But the reason I prefer the straight, prismatic, cylindrical, or wall like shape, in the projections of the new structure, is that this second form of graphic elements give the same impression always regardless of the printing pressure, while projectionshaving an angular end are driven and penetrate into the printing bedding, and the more they do the larger the printed area and thegrayer: the highlights'at sections where a white effect isdesired. If the invention were applied to my formerly patented method, the high-light graphic elements of the outer pattern, or at least the ending part of them, should preferably have a straight-shape. In this last case the combination would include three different relief patterns, the lower of connected graphic elements decreasing in cross-sectional area for half-tones and shadows, the next of similar separate elements for the lighter tones, and the outer one of straight elements for the high-lights.

By selectively distributing suitable opaque matter at the spaces between the cross-lines of the transparent dual patterned support presented as example, this is equivalent to a screen where the lines are the openings and the squares the pitch, as in photogravure. In this arrangement values in surface may be produced at and near the outer part of the coating by a similar tecl1- nique as that utilized in photoengraving. But the complication of obtaining sufficient depth in silver emulsions, specially for coarse rulings, and

the long exposure and elaborate installation required for utilizing in similar manner chromated mixtures, suggested the development of a ready 1 system for producing the photomechanical values by contact printing under an ordinary negative, This other achievement complemented the practical value of the invention.

In my formerly patented method, as explained before, the photomechanical values can be automatically obtained b contact printing due to the angular shape of the projections. But it is not so when the graphic elements have a straight shape as those utilized in the example of dual patterned structure of the present invention. Through a long exposure there will always be some irradiation of the printing light, but never sufficient to develop the proper values at the outer surface of the sensitive coating. I found, however, that regardless of the straight shape of the projections the incidence of the printing light may be so controlled as to develop values in surface in a relatively short time, and I further discovered that even the form of the dot can be modified in contact printing, a result which seemed only possible by changing the outline or relative position of the camera stop in the regular photoengraving process. These achievements were accomplished by a system of mirrors suitably inclined and surrounding the area submitted to the illuminant, In this manner the printing light falls directly on the negative for the action in depth, and indirectly from the mirrors for the development of the values in surface. Varied effects may be attained when a single reflector has the outline of a truncated cone, or when plural ones are arranged as a truncated pyramid having a triangular base, the rotation of the mirror system in regard to the lines of the pattern also affecting the form of the dots. The four mirror arrangement is most suitable for the preferred dual patterned relief above discussed, the side corresponding to the top of the truncated pyramid touching the glass of the printing frame and surrounding the negative, while the more open side corresponding to the base of the figure projecting towards the illuminant, Suitably backed, the mirrors form a simple contrivance that is easily maintained in position by adequate means upon the printing frame. I am aware, of course, that the idea of changing the incidence of light is not new in general for contact printing, at least by two mirrors and for the slight enlargement required in reproducing certain color plates of the prior art. But the mirror surrounded area in contact printing solves an interesting practical problem and seems to be new in graphic reproduction.

The new combination of plural patterns in a single support may not only be useful in its normal relief shape but also in a reversed, castlike form, In a method of Indirect photomeohanical reproduction described in penclingap plication Serial No. 424,582, dated December 27, 1941, now Patent Number 2,374,910, dated May 1, 1945, a mould is produced at once from which a half-tone block may be cast. This mould is obtained by selectively etching a reverse-relief pat.-

tive plates. Still another useful product may be obtained by giving the reverse shape to a coating held on a temporary support, as this can be exposed and then filled with suitable matter and cemented on. a supporting surface before being submitted to the processing.

In order to facilitate the understanding of the present invention it may be convenient to rememher the ways of the classical process. In regular photoengravingthe original is photographed through a screen upon a plate, but in practice photoengraving should not be considered as a simple photographic variation. It is obvious that a negative taken through a screen, as-the processnegativ'e, should show a dotted image wherever there is alight effect, or better, a white field with black dots. However, in the actual processmegative only the half-tone and shadows are formed by black dotson a transparent field, because the high-lights are the opposite, namely transparent dots on a black background. In other words, the pattern of the high-lights is reversed. To reach such photographic contradiction the highlights aredn the first place overexposed through the three stop known technique; then a very contrasty material is used that would hardly record the overexposure of the other values; and finally, for any disturbing halo that might have developed around the dots, a series of reducing or in- 't'ensiiying operations are resourced to which perrnit to say that the process-negative is practically remade and not justobtained by that automatism of the photographic operations. As to the positive, represented by the resist protecting the plate during the etching, it also appears with two. different patterns of which one is reversed in regard to the other, for the high-lights are shown as minute black dots on a white field while the tonesappear as small white dots of diiferent areas on a black background. So the problem confronted in finding a system that would reverse the pattern in a positive by some automatic photographic step seemed an impossibility, specially when the positive had to be built on a relief-pain tern already having the high-light values present and unchangeable. The high-light tint in a relief.v as such, is satisfactory, because it will print small black dots on a white field as the reversed pattern of the positive high-lights in phot-oenra ing. But as the half-tone and shadow, values are not reversed and must show in the positive as white dots on a black background, it is obvious that asingle higlnlight relief pattern formed by dots could not, develop anything but bigger black dots, instead :of white ones, on a White, instead of a black field. For that reason the question was not just to combine in a dual pattern structure a high-light and a half-tone pattern, but rather a negative and a positive pattern, a relief pattern for the high-lights that would develop dots of different sizes and a relief pattern for the halftones that would develop, not dotsbut a black background. So the cross-dine pattern is, in fact, an example of pattern formed by connected graphic elements showing white areas surrounded by black separations which after growing, de-

' lights remain represented in the other pattern by velop the background. for; the required white dots ofthe-half tones and. shadows, while the highseparate small. black dots on a white field. And,

all this, through the invention, is achieved automatically, by simple photographic manipulations.

I the following figures and detailed descriptiori some examples will be presented for demonstration which are not meant to limit. the scope of the invention and its possible variations and applications. i

In the drawings:

Fig. 1V is an example of a relief surface com: bining two patterns in. the same structure. Two.

sections of this figure through the lines 4--4, and

?---TI, respectively, are shown in Fig. 4, anduin Fig. 7. I

Fig. 2 represents the structure. of Fig. 1., after this has been covered with a coating. Twov sections of this figure through the lines 5-'5, and- 8--8,, are respectively shown in Fig. 5, and in i Fig. 8.

' Fig. 3 is the product, after the coated element of Fig, 2, has been processed and transformed into a half-tone printing block. Two sections of this figure through the lines 6--6, and 9-9, are respectively shown in Fig. 6, and in Fig. 9.

Fig. 10' illustrates a relief surface having a screened single pattern of cross-lines which has been suitably overcoated. An area of. the coating has been. omitted in order to show the structure below. A section of this figure through the lines iii-4 2:, is presented in Fig.- 12.

Fig. 11 is the product, after the overcoated ele-' ment of Fig. 10, has been processed and transformed into a half-tone printing block having pure whites. A section of this figure through the lines l3 I3, is shown in Fig. 13. i

Fig. 14 presents a diagrammatic descriptionof a contrivance and step for producing values in depth and in surface when printing by contact. The structure in Fig. 1 combines a half-tone re lief pattern of cross-lines 2, 2,'surrounding the cavities 3., and a-second high-light relief patternformecl by dots I, which protrude from the crossing points of the lines 2, i In the sectional view of Fig. 4, it may be seen how the dots I, are arranged above the lines 2. And in the sectional view of Fig. 7, how the lines are raised from the cavities s. For certain processes, like the example chosen for demonstrating the invention, the

structure f F g. 1, may be screened a the vari-y that the, drawing is purported for illustratingthe relation between the combined graphic elements and not an exclusive materialization, as many possible variations are practicable within the same combination. And also thatthese variations of the example are only. part of many others, for besides the production lithography a variety of other textures may also be obtained according to the main purpose of the invention. In the combination of dots and cross-lines, as explained before, the dotted: pat-e tern is a negative one, for it develops black dots on awhite field; while the cross-line pattern is a positive one for it develops a black background for. white areas. B t between the positive and ne ative atterns there. is a type which may be,

of values; similar to those of photoengravinsand photo-a termed neutral, for it may develop either one. Such is the pattern formed by lines in only one direction, although for the high-lights a very fine line is slightly grayer than the corresponding-dotted pattern. The outer lines, however, may beb uilt upon every other inner line and only in one direction upon a cross-line pattern, the results being then more satisfactory. Lines in one direction are preferable for the lower pattern and may be combined with dots raised at convenient distances along their tops. Lacking abetter-expression to describe the suitable type of graphic element for the halftone, lower pattern, the names of continuous or connected graphic elements have been adopted, as they surround empty areas and because lines are continuous and equivalent to projections connecte'd-in only one direction. The connected elements in the lower pattern are only essential when values are produced similar to those of photoengraving, but not for different textures. That the dots and lines in Fig. l, are only representing the potential relation of the patterns may be further visualized by observing that in a cross-line pattern the tops of the lines may be formed by very close series of dots and still such pattern, for the purpose of the invention, is lineal, because the effect in depth of light through the thickness of the coating will produce the metamorphosis of the dots into lines just as it does for the high-light separategraphic elements in the sections corresponding to the half-tones. Similarly, a cross-line relief-pattern which has been produced by etching, in a dual-patterned structure, may show a slight curvature in depth at the tops of the lines between the protruding dots, and still the relation of the elements will be the same, for that slight arc will be flattened by the exposure intoeven lines at the surface of the coating. Thus, when the expression connected graphic elements is utilized in the description of the invention it must be read as meaning that the elements are linked in one or more directions at some sectional areas; in other words, that their transparency or potential structure is connected or continuous at the fundamental part of the relief regardless of their superficial appearance.

In Fig. 2, the structure of Fig. l, is coated up to the plane passing by the tops of the dots l, I, which are visible at the surface of the coating 4, while the lines have disappeared under it. This is better seen in Fig. 5, where the sectional view shows the dots and the coating terminating at the same plane, while in Fig. 8, the coating ends relatively far above the plane passing by the tops of the lines. In regard to this figure, the limitation of the coating to a plane passing by the tops of the dots should be read as a descriptive expression purportedto illustrate the potentiality of the combination, for in practice, and for some types of separate graphic elements, it may be convenient to slightly overcoat the highlight pattern. Obviously, as there will not be any light effect at the high-light sections, the slight dissolved away leaving uncovered some of the dots i, lines 2, and cavities 3. In the sectional view of Fig. 6, it may be seen how the dots are embodied and disappear into the raise lines at the half-tone an shadow areas, while at the highlight sections they remain isolated and furnish the dotted pattern representing the conventional whites in half-tone reproduction. At the same high-light areas the lines 2, remain under the printing plane and do not show in the impression. But in the half-tone and shadow areas, as shown in Fig. 9, the lines 2, are raised to the operative plane and develop values in surface whose formation will be later discussed.

The coatedelement shown in Fig. 10, includes a supporting structure having only one transparent relief pattern of cross-lines 2, 2, and it would be identical to Fig. 2, if it were not because the dots i, l, are absent, for even the coating, or rather the overcoating of the lines, is the same, as it may be seen by comparing Fig. 8, and Fig. 12. Another feature added to this type of element, and which may be useful for producing the values in surface through certain optical operations, is the screening means 5, which appears at the bottom of the cavities and in the spaces between the cross-lines. This ives the supporting structure the appearance of a photogravure screen in which the openings or lines are in relief. The support in Fig. 10, may also be used without the screening means, as already explained. The screening means 5, has been illustrated as black or opaque as preferable for general purposes. But when the values are to be formed by contact printing, as in the chosen example, a partial absorption. of light would do it sufficient to reduce the thickness of hardened matter at the bottom of the cavities for convenient depth of the printable values.

In Fig. '11, the product obtained from the element of Fig. 10, is illustrated. For the sake of comparison it has been assumed that the subject which has been reproduced is the same as in Fig. 3. The outer areas of the undissolved coating 4x, are substantially the same in both products, as it may be seen by comparing Fig. 9, and Fig. 13; but the bare dots I, present at the high-lights of Fig. 3, are missing in Fig. 11. When printed, the element of Fig. 3, will show dotted high-lights, while that of Fig. 11, will have pure whites, as the so called lithographic halftones.

In Fig. 14, the diagram shows four mirrors 6, 6, whose arrangement follows the outline of an upside-clown truncated pyramid of" rectangular base. The top of the figure is positioned in contact with .the glass of the printing frame 8, so as to enclose the area corresponding to the negative 9, while a rubber band and clips Ill, hold the contrivance in place for the exposure. The figure is purported to illustrate the device and the step for producing in contact printing a similar effect as that obtained by the camera in photoengraving for the formation of photomechanical values.

For practicing the invention I begin by producing the structure of Fig. 1, in a master plate from which I take a mould and subsequently as many casts as I may need. Or I may at once produce a reverse structure from which I cast the dual patterned relief. In the example pre sented the ratio of the cross-line pattern is 1:2, in order to facilitate "the graphic'difference between dots and lines, but I may use any other suitable ratio as the usual 1:1 in photoengraving or the 1:4 inphotogravure. When mechanical engraving is utilized the plaster plate l nses in three successive operations: a 'revers'e pattern of cross lines is out with a suitable stylus on a metallic surface, the depth of the grooves crossing points where the dots remain protrud ing as required. From the niaster plate I inay take a mould by electroplating; or in man "other known ways. :When the mould is finished, 1 stamp with'it some transparent, pressure 'resist ant material, as some plastics on the market, which are suitable for the example chosen in the present disclosure. Y

There are other ways of producing the roaster plates. For instance, a'sma'll section of the dual pattern may be engraved by hand, and then plural matrices taken in order to multiply the relief in the fashion of type-casting or in that of typesetting machines. It is also possibleto out down a mechanically produced -cross=line relief pattern as in re-etching, carrying the operation far enough as to undercut the lines; which at the crossing points offer more resistance, thus leaving protruding dots. A mould may also be illrectiy produced by forming a resist of parallel lines on a metallic surface and etching it; forming then a second resist perpendicularly to the first, and etching the "plateagain; 'whereby the plate will be etched twice at the crossing of the lines and the grooves will cast protruding "dots at those sections. The same result may be obtained through a carbon tissue resist suitably exposed, and in many other ways.

"While the dual patterned relief may be conveniently cast in plastics for the use her'efr'om presented as an example, the structure may also be produced in opaque and even flexible matter for other purposes, as there are several relief rocesses in which it could be utilized, and also varied ways-of adding supplemental values'to the fundamental relief pattern "of the invention.

For washwii processpurposes i coat tliedual pattern reiief oi transparent plastics with a en sitive composition. This ma be a suitable silver emulsion, but I will prefer for demonstration a sin'ipie mixture of chro'niated gelat-ine which I extend on the support onf its reliefsid'e arid in sufiicient quantity as to fill it, when dried, substantially up to the ending plane of the projec= tions forming the high-light outer pattern. F-Jhenihsteadoi using 'thestructure of'Fig. 1, as a support, I utilize the single patterned one of Figs. ill, the amount of "coating "is substantially the same, so that'the cross' 'line" pattern will be equally overcoated in both cases; Afterthepla'te is dried i expose it. through its support under an ordinaryphotographicnegative, and for that exposure-I place and fix' on the printingfraine the mirror system illustrated in Fig; 14'.

When the illuminant falls upon the negative; assuming that the beam is of parallel light, which may not be indispensable, the light effect is produced in five directions, one straight from the source'of light; which only 'develops'v'alues in depth and, by hardening the coating, 'automat'l cally raises'the cross-line relief pattern to an operative plane; and in four more" directions from the mirrors, each onesendin'g light at any desired incidence, which develops values in "surface at the outer part o"f"thesehsitive coating The light in th is last-case penetrates-thermos parent projections of the supportin angular 10 was and affects the part of the coating present at the sides rather than that above the tops or the graphic elements in the crossed-linepattern.

After exposed the plate is treated in wash-off way as to dissolve the unhardened part of the coating. 'Wh-en dried, the product is finished be proo fcd, mounted and printed.

support of ig is, when wholly transparis sirnilar to a structure known to the art which was suggested for producing pseudo-gm vure printing plates by the wash-off process. And the sarne may be said of the coated plat-e, 'aithongh the similarity in both cases is only ap pa-i it. in regard to the old support it must be not edthat according to authorities the depth of gravu-re pockets is not greater than 3 thousandths of one inch. For the purpose or the invention a depth of 3 thousandths of one inch is much shorter than what is necessary, as we are now producing pseudo ,photoen'g'ra'ving and not 'intaglio plates. The known average depths for different rulings in printable half tone blocks are in thousandths of one inch:

Soreculin'cs High-lights Half-tones Shadows If we assume that :in a wholly transparent support the height of the lines or walls is only 3 thousandths of one inch, and that the thick ness of the coating above the lines is also '3 thousandths of one inch, :it is obvious that the light :efiect in depth only, which liar-dens and raises the lines to the operative plane, will also raise the bottom of the cavities in the same 3 .tho-iusandths of one inch, and. the height will not be changed. But when the values in suriacefare produced .by the lateral effect of the lig-hhithere is an additional thickness to be subtracted .irom that depth which may reduce in more than one .half, the assumed 3 thcusandth's of one inch. I

have foundthat for rulings which may be considered'as coarse, like 55, 85 and 100, the height of the :lines will not be sufficient even if they are given the high-light depth, because the :additional-side light effect so reduces that depth that it-would not meetthe numbers of the second column; and further, that it is necessary to give them an extra height. The pockets for these coarse rulings may require a depth in thousandths of one inoh approxiinately of ll-to-12 for 55;- 6- tol. for the 85; and 4.5-to-5 for the 100 line rulings, which is about from two to four times the maximum depth of 3thousandths of one inch in gravure pockets. For finer rulings, as 120, 150, and 1751ines, the situation is more aggravated because the amount of matter is greatly reduced and theiri'adiation of the printing light together with the reflections and glare in the enemy transparent support calls for a height of more than twice the corresponding average high-light depth. "Itnnay be safely established that for .a 'transpa en't support the height of the walls should be from about a minimum of 5 for thefineto about a maximum of 15 thousandths of one inch for the coarse rulings, respectively,

and cavities of that depth 'are'not grav'ure peckets nor could-they be used as'such. The requiremerit of depth in the support of the invention is acon dition of operativeness for a new purpose which does not suit the old one. And such new support is an article of manufacture which may be coated by the worker himself.

Another solution for the problem of printing depth is illustrated in 5, Figs. 10, 11, 12, and 13. Such or any other equivalent means suitable for attenuating or eliminating the effect of light in depth at the bottom of the pockets, permits to raise the height of the lines 2, by hardening the coating above their tops, Without producing the same effect at the bottom, thus gaining in printing depth, While the lateral action of light at a suitable incidence will not have any substantial effect on it. Naturally, the screened support allows much more margin for shortening the height of the graphic elements in the relief pattern to the minimum operative depth, favoring definition, and even economy. But while the height of the walls in the screened element may fall now for some rulings within the depth of gravure pockets, such screening means brings another differentiation, because it would be contrary to wash-01f intaglio anything that would interfere with the passing of light through the bottom of the pockets, as it is through those transparent areas that the values are formed, while in the process of the invention the useful exposure is only the one made through the walls and not through the pockets of the support.

A relief pattern provided with screening means is not new in the art in general. In my formerly patented method of reproduction a similar arrangement may be found among variations of the support. In that case, however, the opaque sections form a cross-line pattern of black lines as in a photoengraving screen, while in the invention the operative structure must have transparent connected sections as in photogravure. The screened support of the invention is further differentiated from photogravure screens in that these have the pitch and the openings at the same level in order to secure good contact with-the carbon tissue, while in the support of the invention the transparent lines are raised and even printable as a relief surface.

In regard to the coated plate, which may be sensitive to light or susceptible of being sensitized, the novelty of the combination is not only in the supporting element, but in the coating element, for the thickness of this does not end at the plane where the walls terminate but relatively at a much higher plane, as shown in Fig. 8, which is a section of Fig. 2, but would be identical to a similar section of Fig. 10, with a wholly transparent support. The extra thickness of coating in this case may corespond to the average depth of the half-tone values in printable blocks, and in practice it must be such that when some of the lines have been raised to the end of the coating, those other lines which remain bare will not print. This is another difference with the sensitive plates in pseudo-intaglio processes. where the coating must not project beyond the plane passing by the tops of the walls, and with the sensitive elements of my formerly patented method in which the coating ends substantially at the vertices of the projections. And so, whether provided with a wholly transparent or screened support, the sensitive plate of Fig. 10, is also a new and useful article of manufacture.

The contrivance illustrated in the diagram of Fig. 14, considerably shortens the exposure. In sunlight a four mirror system will throw upon the image area about five times the normal amount of light. This will counteract the low sensitivity of certain mixtures, and in comparison with any system in which the normal amount of. light would produce both the effect in depth and in surface, that of the invention is obviously much faster. In photome chanical reproduction, the new device solves a most interesting problem by achieving results that formerly were only obtained by means of the camera in the classical process. The new article may also find some applications in photography and may be manufactured to fit different standard sizes of printing frames.

As to the novelty of the products we must consider first the one illustrated in Figs. 3, 6, and 9, which is built upon a dual pattern structure, and then that of Figs. 11 and 13, which renders a half-tone impression with pure Whites. Both products are seemingly new and both are useful; The printing plate of Fig. 3 is differentiated from the products of my formerly patented method of reproduction in that the half-tone printing areas are not black dots on a white background but white areas on a black field because they are not developed from high-light printing elements carrying different amounts of additional matter but from a half-tone pattern formed by connected elements which develop a black background and are raised by the exposure to the operative level of the values. The printing plate of Fig. 11 is differentiated by the fact that the single relief pattern is not formed by separate and sharp- 1y ending elements of high-light printing areas but by a half-tone pattern of connected elements, and because the values are formed above and not at the ending plane of the pattern, for the whites are pure, without the minimum dot. In fact the product of Fig. 3 is the same as that of Fig. 11, with additional dot printing projections at the white areas to match the appearance of regular half-tones.

That the two forms of the invention are not a superfluous repetition of the same preferred result may be easily realized in practice, for halftone values for lithographic purposes may be obtained through the invention and suitably transferred, 2. case in which the minimum dot in the high-lights is undesirable. On the other hand, while half-tone blocks with pure whites may also beutilized in typographic printing, it would all depend upon the size of the white areas, for when these are too large the minimum dot is necessary. It may be said, however, that the possibility of cutting off sections from a plastic plate is much easier than routing, should the pure white kind of impression be specially desired. Such possibility has been taken in consideration when limiting the thickness of the overcoating in the element of Fig. 10, to approximately the average depth of half-tone values in printable plates, for while the overcoating could be somewhat thicker, the thinner it is, the better the definition and the finer the results.

About the coating 4, adopted for the demonstration, and which has been described as a simple mixture of chromated gelatine, this does not necessarily imply that it should be used plain, for there are many additions well known by those skilled in the art which may favor the results of the processing. Some dyes may conveniently modify the transmission of light through the coating; and some pigments, or unsoluble precipitates can be added which facilitate the inspection duringthe development. Of these I may utilize some which set at the bottom of the cavities and provide selective screening means; or I may deposit some light screening matter at the bot tom of the cavities before the-coating-is; spread and incorporates it, etc. It mustv be explained, besides, that when coatings are described. as sensitive matter in the present specification, it does notprecisely mean that they should be so when applied to the supports, but at the moment of using the articles, for specially in bichromate variations, as the chosen example, it is rather convenient to sensitize the elements shortly before. using them; thus by sensitive to light it must be understood both those coatings which are actually sensitive and those which are suseep'tible of being sensitized. The expression sensitive matter, instead of sensitive coating" has also been preferred, because the matter may be applied to several coatings, and even in difier'ent coatings including emulsions of varied composition or chromatic sensitivity, and. that expression generically covers secondary variations which would be prolix to enumerate.

We have so far discussed the production of values similar to those obtained by photoengi'aw ing and photolithograpliy, but a variety of other textures may also be obtained according to the purpose of the present invention.

The-new way of producing"photomeehanical values relief patterns having projections of straight shape and thus more adapted to changes in the printing pressure without a darkening effect in the high lights, lends itself to obtain a variety of other textures in values formed upon relief-patterns with less combination than the types illustrated in Fig. 1 and Fig. 10. Such variauons may utilize dual and even single patterned supports already known but heretofore never utilized in a sensitive plate. Or they may employ new structures simplifying the features of the examples, as dual patterns may be combined independently at different levels, or one built upon the other without graphic elements or the connected kind in the lower pattern. It is obvious, of course, that the more such patterns approach the preferred illustrated types the better the rendition of the tones. But this cannot be stated asv a rule, because in a system of exposure which sends light from several directlons at any suitable incidence, many a pattern of apparently disconnected elements ma link those elements laterally, just as the effect of light in depth equals the height of elements situated at different levels. And the further step of modifying the form of the texture by convenient rotation of the reflectors also offers the possibility of breaking the monotony of known patterns for the most varied effects.

The novelty of the coating element in the plate combination, in a thickness surpassing the level. of a relief pattern in su'iiicient printing depth, is not only a condition in the preferred sensitive, elements of Fig. 2 and Fig. 10, but a combination itself which may. prove to be very useful in modernreproduction processes. A support having a, dual or even single patterned reliefformed by projections of high-light printingareas, when so overcoated, will permit to produce aline design in raised values without resourcing to, routing because, besides the depth of the values, the pattern at the bottom will provide a,

safeguard by furnishing a very fine dotted texture in which the printing pressure will be so lessened as to make it practically invisible in eventual impression, depth and fineness which,

can; hardly beproducedby etching in the classi'-- cal process. It is an ideal combination which 14 I have successfully used for speedy reproduction of text from photocomposing machines.

During the course of the above description same as in the claims defining the invention a geometrical language has been adopted to facilitate the understanding of the principle and materialization of means, ways, and products. Terms have been employed such as cones, triangles, bases, vert'ices', ending planes etc. As such lairguage :niay convey a mathematical and exact meaning it must be understood that within the limits of operativeness, it is not meant to so liinitv the invention in practical manufacture.

After having described'to the best of my knowi edge the new and useful improvements, I wish to be understood that the present disclosure for the purpose of illustration only and that the invention includes any variations, equivalents and applications within the scope 'of the fol-lowingclaims.

I claim:

1. In pho-tomechanical reproduction, a foundation which combines in the same body plural elevated designs of different heights, each of said designs formed by a number of minute elevations which for the same design substantially have the same area, the minute elevations in the lowest design raised from the bottom of the structure, and those of successive designs built upon theminute elevations of the design below and correspondingly showing a lesser area.

2. In vph'otomechanical reproduction a support combining at least two different relief formations in successive elevation, the first of said formations showing an evenly distributed number ofsmallprojections, and the second formation exhibiting a second number of minute projections of lesser area built upon those of the first formation, said support presentinga sectional appearance of a half-tone tint at a plane passing by the tops of the first number of projections, and that of a high-light tint at a plane passing by "the end of those of lesser area.

3-. In photomechanical reproduction, a relief surface combining two different groups of graphic projections, respectively situated at-t'wo different planes, and one built upon the other, the first grou of projections consisting of connecte'dsmau elevations from the bottom of the structure, and the second group or smaller and disconnected elevations from the tops of the connected ones;

4 In photomeohani'cal reproduction, a base showing a bottom, a first elevation from this bottom exhibiting a graphic texture of small projections, and a further elevation from the top areas of these projections forming-a second and finer graphic texture of uniform projections of lesser area.

5. A photogra hic support embodying the combination of two re-lief formations situated one upon the other, the lower formation exhibitinga number of light transmitting and continuous minute elevations raised from the support, and" 7. An element showing the-reverse shape of't he' structure described in claim 3.

,8; In photomechanical reproduction, the combination in a unit of a tint platesuitable for typo"- graphicprintin'g and a pho'togravure screen, said tin't plate showing'elevations and depressions, the elevations. corresponding ;to the op enlngs of the 15 screen; and the depressions to the pitch of the same, said elevations presenting the appearance of transparent thin walls of straight shape and uniform height limiting opaque areas.

9. In photomechanical reproduction, a wholly transparent support for a sensitive coating, said support showing at one side wall-like elevations of straight shape surrounding pocket-like depressions in arrangement similar to a shadow section in a screened gravure plate, except that the depth of said depressions surpasses in more than one half the operative known maximum depth of gravure pockets, the depth of said depressions also surpassing the average known depth of the highlights in printable half-tone blocks of equivalent ruling.

10. In a photographic element, a light-transmitting support showing on one side two different series of minute elevations at different levels, the higher elevations having a smaller area than those of the lower series, and matter sensitive to light coated on said support at least to the top of the higher elevations.

11. In a photographic element, a light-transmitting support provided on one side with two diiferent relief patterns, one of said relief patterns formed by minute and separate projections representing a high-light tint, and the other relief pattern formed by connected projections representing a half-tone tint, the projections in the first pattern built upon sections of those in the second pattern, and matter sensitive to light filling the relief of the combined patterns up to a height at least equal to that of the high-light projections.

12. In a photographic element, a support havingon-one side a sensitive coating, said support provided on the coated side with at least a series of minute projections forming a printable tint; both the projections and the areas in the support from where they are elevated transmitting light and offering a path to it for reaching from the uncoated side the inner sections of the coating surrounding and covering the minute projections; said coating having a thickness which when retained at some places will make the difference in height such between the coating and the support that the minute projections will not print.

13. In a photographic element, a transparent support showing on one side pocket-like minute depressions surrounded and isolated by wholly connected walls, the depth of said depressions from about two to four times the known maximum operative depth of gravure pockets, and matter sensitive to light coated on this side of the support in a thickness surpassing the height of the walls in at least the depth of half-tone values in printable blocks of corresponding ruling.

14. In a photographic element, including a transparent support having on one side at least one relief design formed by wholly connected projections surrounding and isolating pocket-like depressions, matter sensitive to light coated on said support, and second matter capable of absorbing light mixed with the sensitive matter at the bottom of the depressions.

15. The method of producing by wash-off a half-tone block with values similar to those of photoengraving which consists in, first, providing a transparent support having on one side two relief patterns of difierent heights, the higher pattern formed by minute and separate graphic elements representing a high-light tint, and the lower pattern formed by connected graphic elements representing a half-tone tint, the graphic elements in the higher pattern being raised sections of those in the lower one; second, coating said support with matter susceptible of being selectively and proportionally hardened at the areas exposed to light, the thickness of that coating reaching the tops of the graphic elements in the higher relief pattern; third, exposing to light the coated plate through its support under an ordinary negative so as to reach the surface of the coating with the light effect in those sections corresponding tothe tones of the image; fourth, further submitting the same to light of suitable incidence from several directions around the area of the printing negative; and fifth, treating the exposed coated plate by the wash-off process.

16. The method of producing by wash-off a half-tone block with pure whites similar to those of photolithography, which consists in, first, providing a transparent support having on one side a relief pattern formed by connected graphic elements representing a, half-tone tint; second, coating said support with matter susceptible of being selectively and proportionally hardened at the areas exposed to light, said coating surpassing the level of the relief in a thickness sufficient to make the same unprintable when areas of the coating are retained upon it; third, exposing to light the coated plate through its support under an ordinary negative so as to reach the surface of the coating with the light effect in those sections corresponding to the tones of the image; fourth, submitting further the same to light'of suitable incidence from several directions around the area of the printing negative; and fifth, treating the exposed coated plate by the wash-off process.

17. The method of producing a printing block which consists in first, providing a support for a sensitive coating having on one side at least one design in relief exhibiting a number of elevated and minute graphic elements forming a printable tint, said minute graphic elements and the sections in the support from where they are elevated both transmitting light and offering a path to it for reaching from the other side of the support the inner areas of a coating surrounding and covering said minute graphic ele-' ments; second, coating said support with matter sensitive to light in amount to surpass the tops of the elevated minute elements in a thickness sufficient for making the same unprintable when portions of the coating are retained thereon; third, suitably exposing the coated plate through its support under an ordinary negative so as to reach with the light effect the sensitive matter both upon and around the minute elevations in proportion to the values of the printing negative; and fourth, submitting the exposed plate to a relief process capable of removing the coating from the support except in those areas occupied by the values to be reproduced.

18. A printing block, including a base showing a number of minute elevations of which some are substantially bare and some others carry different amounts of additional matter increasing their height and width to form printable relief values which coincide with those minute elevations upon and around which they are respectively built, each one of these values being thus necessarily supported at least by one minute elevation; the thickness of said additional matter raising the printing plane of said values to a level which makes the bare sections unprintable. 19. A half-tone block, including a base, a

graphic texture elevated from said base, and different amounts of additional matter retained thereon; said graphic texture formed by wholly connected projections in wall formation surrounding and isolating pocket-like depressions, some of said elevated walls appearing substantially bare at the sections of the high-lights, and some others increased in height and width by said additional matter to form half-tone and shadow printable values which coincide with those connected projections upon and around which they are respectively built; the thickness of said additional matter raising the height of said values to a level which makes the bare projections unprintable.

20. In a half-tone block, a relief pattern formed by connected graphic elements representing a half-tone tint, said graphic elements having raised sections forming a second pattern of separate graphic elements representing a high-light tint, additional amounts of matter substantially raising the height and increasing laterally the areas of the connected graphic elements up to the level of the separate elements, said additional matter forming half-tone and shadow printable values, and the separate elements representing the high-light tint remaining partly embodied into the matter raising the connected graphic elements, and partly standing separately and furnishing a dotted pattern for the high-lights.

F. G. YANES.

REFERENCES CITED The following referencesare of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 926,377 Albert June 29, 1909 1,128,665 Dittman Feb. 16, 1915 1,166,540 Orans Jan. 4, 1916 1,240,344 Ives Sept. 18, 1917 1,592,358 Hatt July 13, 1926 1,600,447 Woods Sept. 21, 1926 1,838,218 Durham Dec. 29, 1931 1,849,036 Ernst Mar. 8, 1932 1,909,939 Ernst May 23, 1933 1,961,348 Goedtler June 5, 1934 1,991,888 Ernst Feb. 19, 1935 2,093,063 Wesstrom et a1. Sept. 14, 1937 2,234,997 Yanes Mar. 18, 1941 2,304,988 Yule Dec. 15, 1942 2,323,752 Howey July 6, 1943 FOREIGN PATENTS Number Country Date 9,170 Great Britain Apr. 11, 1914 730,256 France May 9, 1932 

